5.3" Lustrous Sulfur Crystals on Sparkling Calcite - Poland

Calcite, CaCO3, is a carbonate mineral and the most stable polymorph of calcium carbonate. The other polymorphs are the minerals aragonite and vaterite. Calcite crystals are trigonal-rhombohedral, though actual calcite rhombohedra are rare as natural crystals. However, they show a remarkable variety of habits including acute to obtuse rhombohedra, tabular forms, and prisms. Calcite exhibits several twinning types adding to the variety of observed forms. It may occur as fibrous, granular, lamellar, or compact. Cleavage is usually in three directions parallel to the rhombohedron form.

The chemical composition of this vibrant mineral is S8, eight sulfur atoms bonded together to form a sulfur molecule. The crystal structures are typically tabular or blocky dipyramids that form in sedimentary rock.

One note on handling: sulfur crystals can crack when exposed to rapid changes in temperature.